Field of the Invention
The invention relates to a method for parameterization of a field device. At least one parameter value is transmitted to the field device from at least one parameterization unit. At least one parameter value is received by the field device. At least one feedback character string is generated from the at least one received parameter value by the field device. The feedback character string is transmitted to the parameterization unit by the field device. The received feedback character string is output by the parameterization unit so that it is understandable for the user and, in particular, is visually displayed. Furthermore, the invention relates to a field device having at least one interface for connection to a parameterization unit, at least one control component, and at least one data storage device. The control component generates at least one feedback character string from at least one parameter value received by the field device.
Description of Related Art
In modern process automation, such as in processing plants, field devices are used for monitoring process variables (e.g., fill level, flow, temperature, pH, etc.) and actuators for influencing the processes or process variables. The communication between the field devices and, for example, a control room occurs using fieldbuses, wherein different data protocols (e.g., HART, PROFIBUS PA, 4 . . . 20 mA, etc.) can be used for the transmission of measuring or control data.
Additionally, it is also provided, in part, that the field devices have their own display units (i.e., “displays”—that can be used to present, for example, measuring data or further values of the field device. It is possible to directly influence the field device via a display and, optionally, in conjunction with a type of keypad on the field device itself, or via a corresponding interface on the field device and an operator unit in order to, for example, start programs, enter or choose parameters.
Thus, many field devices have at least two output possibilities: an interface for the connection of the field device to a fieldbus for data connection; and a display unit for on-site presentation. Additionally, there is optionally the aforementioned input unit, for example, in the form of a keypad or some knobs on the field device; or the service interface for connecting an external unit, such as a so-called “handheld,” or a portable computer in the form of a laptop.
It is problematic when the data connection itself is not secure and when, at the same time, the use of the field device is security-sensitive. If, above all, the field device is parameterized, how it should function and at which calculation values, limitation values and control values it should function is set, so that it is of great importance that the parameter values are safely and reliably set in the field device.
Where necessary, guidelines are also relevant in the respective security requirements in order to fulfill important SIL (“safety integrity level”) standards in process automation.
Not only data communication between a parameterization unit and the field device can be unsafe and thus critical in this situation, but also individual components or elements of the field device can be unsafe.
A similar method for parameterization of a field device is described in European Patent EP 2341406 B1 (which corresponds to U.S. Pat. No. 8,634,938 B2). A parameter value is transmitted from a parameterization unit to a field device and stored read-only. The field device transmits the received parameter value back to the parameterization unit, namely in a format that cannot be processed by the parameterization unit. This, in particular, is a text format, so that the parameter value is fed back as a character string. Additionally, the name of the parameter and a confirmation code are transmitted. The confirmation code is, in turn, sent back to the field device after a comparison of the re-transmitted parameter value with the supplied parameter value.
International Patent Application WO 2006/053668 A2 (which corresponds to U.S. Pat. No. 7,912,990 B2) describes a method for parameterization of a device, wherein the parameter values are fed back from the device to the parameterization unit at least once for monitoring.
For sending parameter values from a parameterization unit to a field device, it is proposed in German Patent DE 10329407 B4 to send them as a character string using the HART protocol.
To ensure that all parameters are unchanged after a re-boot of a field device, it is suggested in German Patent Application DE 102011088236 A1 to determine from the parameter values a checksum at a first time and a further checksum after re-booting and to compare the checksums to one another.
The implementation of parameterization of a field device according to German Patent Application DE 102010062908 B4 (which corresponds to U.S. Patent Application Publication 2013/0261772 A1) is similar, in which it is provided that a checksum is generated and displayed for the parameter values by each the field device and the parameterization unit and that a user compares the checksums to one another.
In parameterization of field devices, consideration must be made in regard to the used components and transmission paths, insofar as errors can sneak in therefrom. Thus, one goal is to avoid, as much as possible, that defective or unsafe and thus possibly error-prone components or unfortunate chains of errors lead to the safety of the parameterization being jeopardized.
Simultaneously, it should be possible to carry out parameterization even in unfavorable conditions. For example, in the case that the field device cannot be directly or easily reached, so that, for example, a display on the field device is rarely or not always of assistance. Parameterization should, thus, always be optimized in consideration of practicability.
In particular, it should be additionally ensured that the field device is integrated in the process of parameterization or in the process of confirmation of the parameter value and that e.g., the parameterization unit does not just copy data. The reason for this is that the parameterization unit, depending on the design, takes over two roles: input of the parameter value and feedback of the parameter value. Thus, it must be guaranteed that the parameter value is really transmitted to the field device and is sent back from there.
One step in that direction is, inter alia, the use of character strings or text data, which cannot be understood or used by the involved devices (parameterization unit or field device) or by their components. Thus, the possibility of influencing the flow of information is limited or such influence is more easily recognizable.